The present invention relates to a portable information processing apparatus that includes a main body and a lid that is so attached to the main body that it can be freely opened and closed.
Currently, so-called notebook personal computers, which are one type of portable information processing apparatus, have come to be widely used because of their portability. The background will now be explained by using a notebook personal computer as an example.
A notebook personal computer includes a main body and a lid that is so attached to the main body that it can be freely opened and closed. A keyboard is provided on the top face of the main body for inputting data. The lid includes an LCD unit for displaying the data that are inputted at the keyboard, and a cover on the back face of the LCD unit.
FIG. 6 illustrates a lid 100 of the a conventional notebook personal computer. An LCD unit 104 with a rectangular cross section is retained in a rear cover 102 of the lid 100. A gap 106 is defined between a side wall 102A, which is near the center of the rotation of the rear cover 102, and side edge of the LCD unit 104 opposite to the side wall 102A. Hinges 108 of a torque plate pressure type are provided in the gap 106. These hinges 108 couple the cover 100 with the main body so that the cover 100 can be freely opened and closed.
FIG. 7 is a perspective view of the hinge 108 shown in FIG. 6. As is shown in FIG. 7, the hinge 108 has a crank-shaped attachment piece 110 that is fixed to the main body, and an L-shaped attachment piece 112 that is fixed to the rear cover 102 of the lid 100. The attachment pieces 110 and 112 are coupled together by a shaft 114 which is fixed to the distal end of an arm 112A of the attachment piece 112, so that both pieces are relatively rotatable.
More specifically, a seating disk 118, which has a protrusion 116 at a predetermined position on its circumference, is integrally formed with the shaft 114 passing through its center. A support 110A, whose distal end is formed in a ring shape, projects upward from the attachment piece 110 and is inserted at the position adjacent to the seating disk 118. A hook-shaped stopper 120 that can engage the protrusion 116 is integrally formed with the external surface of the distal end of the support 110A. A notch 122 is formed in a predetermined position at the distal end of the support 110A. A torque ring 124 is provided adjacent to the support 110A. A hook-shaped pawl 126 is integrally formed at a specific position on the circumference of the torque ring 124, so that the torque ring 124 engages the notch 122 with the pawl 126. A wave washer 128 and a presser ring 130 are assembled adjacent to the torque ring 124 in the named order, and are secured. In short, the hinge 108 is the type that generates torque by friction.
With the above arrangement, when the lid 100 is opened and closed, the one attachment piece 112 rotates relative to the other attachment piece 110, and the wave washer 128 rotates on the face of the torque ring 124. When the lid 100 is opened, a torque generated by the friction between the wave washer 128 and the torque ring 124 ensures the lid 100 being held at any desired angle.
The size known as A4 is a popular size for a notebook personal computer. Although the conventional LCD panel of the notebook personal computer is commonly 10.4 inches and can be easily included in the size A4 footprint, recently there has been a tendency to increase the size of the LCD. The employment of a larger panel, say a 12-inch LCD panel, has also been discussed and recommended. As the LCD panel becomes larger, however, it occupies more space inside the lid, so that the room for accommodating other components, such as hinges for coupling the lid with the main computer body, is accordingly reduced. In this case, the above described hinge structure may be accepted, but problems arise.
Since the hinges 108 are a torque plate pressure type, the maximum torque is limited by the diameter of the torque plate 124, which cannot be greater than that which can be accommodated in the rear cover 102. Because the hinges 108 generate torque in proportion to the length in the direction of the shaft diameter, the diameter of the shaft 114 can't be excessively reduced. If torque plate pressure hinges that are narrower than the current hinges 108 are employed, they can not produce the torque (on the order of 60 kg or greater) required to hold a lid with a heavy 12-inch LCD unit at any desired angle. If the hinge of the type like the hinge 108 is to be employed at a venture, the lid must be thickened or the foot print of the lid must be expanded to provide sufficient room for accommodating the hinges. This, however, degrades the features of the notebook personal computer, that is its compact size and its excellent portability.